(i) Field of the Invention
The present invention relates to a copolymer of acrylamide or acrylamide derivative and of trialkylammonium salts which exhibits a biocidal nature and is intended in particular for the coating of substrates.
In the following description, the invention is more particularly set out with reference to a copolymer for the impregnation of a textile substrate, but, of course, it should not be regarded as being limited thereto, it being possible for the copolymer of the invention to be applied to other substrates, such as leather, wood or plastic substrates.
The term xe2x80x9cbiocidalxe2x80x9d is understood to mean the property which consists in destroying a microorganism, such as fungi, yeasts or bacteria. More specifically, the copolymer which is the subject-matter of the invention exhibits, and confers on the substrate to which it is applied, a contact biocidal nature, which means that it directly brings about the death of the microorganisms by simple contact.
The present invention is mainly of advantage in the medical field, where the need to have available means for protecting against pathogenicagents is ceaselessly increasing.
(ii) Description of the Related Art
The properties required for a textile for medical use are, first, a biocidal effect and good absorption of liquids.
A biocidal or antiseptic compound corresponding to the following formula:
[H2Cxe2x95x90C(R1)xe2x80x94Bxe2x80x94(CH2xe2x80x94CH2)nxe2x80x94N+(R2)(R3)(R4)]Xxe2x88x92
in which,
R1 represents H or CH3,
R2, R3 and R4 each represent an alkyl group such that the total number of carbon atoms of R2, R3 and R4 varies from 6 to 15,
n varies from 1 to 3,
B represents CH2, a carboxyl functional group or an amide functional group, and
Xxe2x88x92 represents a counterion,
is known according to the document FR-A-2,695,800.
The compound disclosed is used for the preparation of biocidal fabric cotton textile under conditions of grafting the compound by radical activation under the effect of ionizing radiation, such as xcex3 radiation.
The manufacture on an industrial scale of a biocidal textile as disclosed according to FR-A-2, 695, 800, and more particularly the stage of grafting the compound to the substrate, represents a very heavy technological investment and, furthermore, requires a workforce necessarily trained in nuclear techniques, due to the harmful effects of such radiation.
The Applicant Company has discovered a biocidal product which makes it possible to solve the problem posed by known biocidal compounds by introducing a product which can be attached to a substrate by simple impregnation. In particular, when. the substrate is textile, the attachment of the product can be carried out by standard techniques of this industry, in particular padding.
The product of the invention consists of a copolymer which can be obtained by radical copolymerization, in the presence of an initiator,
of at least a first monomer chosen from acrylamide and its derivatives of formula
H2Cxe2x95x90CHxe2x80x94(CH2)nxe2x80x3xe2x80x94CONH2
xe2x80x83in which nxe2x80x3 is an integer which can vary from 1 to 5 and advantageously from 1 to 3;
and of a second monomer chosen from trialkylammonium salts corresponding to the following formula (I)
[H2Cxe2x95x90C(R1)xe2x80x94(CH2)nxe2x80x94Axe2x80x94(CH2)nxe2x80x2xe2x80x94N+(R2)(R3)(R4)]X+xe2x80x83xe2x80x83(1)
xe2x80x83in which,
R1 represents H or an alkyl group having from 1 to 3 carbon atoms,
R2, R3 and R4, which are identical or different, each represent an alkyl group having from 1 to 3 carbon atoms,
n and nxe2x80x2 each represent, independently of one another, a non-zero integer at most equal to 15,
A represents a divalent carboxyl or amide functional group, and
Xxe2x88x92 represents a counterion.
Preferably, the first monomer is acrylamide or else the second monomer corresponds to the abovedescribed formula (I) in which n varies from 7 to 9, nxe2x80x2 varies from 2 to 4 and Xxe2x88x92 represents Clxe2x88x92, Fxe2x88x92 or an alkyl sulphate ion.
The second monomer advantageously corresponds to the abovedescribed formula (I) in which R1 represents H; R2, R3 and R4 are identical and each represent the methyl group; n is equal to 8 and nxe2x80x2 is equal to 3; A represents the amide functional group; and Xxe2x88x92 represents the methyl sulphate ion.
As will be illustrated in the examples at the end of the description, a particularly advantageous copolymer according to the invention is that which can result from the copolymerization between the preferred first monomer and the preferred second monomer identified above.
More advantageously still, the weight-average molecular weight (Mw) of the copolymers is between 6000 and 10,000.
According to an alternative form of the invention, a copolymer can consist of a terpolymer which can be obtained by radical copolymerization at least of the first monomer, of the second monomer and, in addition, of a third monomer chosen from acrylic acid and vinyl esters. Mention may be made, as examples of such esters, of vinyl acetate, vinyl propionate and vinyl butyrate.
Another subject-matter of the invention is a process for preparing a copolymer defined above. It comprises the stages consisting in reacting at least a first monomer, a second monomer and optionally a third monomer, as have been defined above, in a solvent at the reflux temperature, in the presence of an initiator.
Preferably, the first monomer is acrylamide and/or the second monomer corresponds to the formula (I) in which n varies from 7 to 9, nxe2x80x2 varies from 2 to 4 and Xxe2x88x92 represents Clxe2x88x92, Fxe2x88x92 or an alkyl sulphate ion.
The second monomer advantageously corresponds to the formula (I) in which R1 represents H; R2, R3 and R4 are identical and each represent the methyl group; n is equal to 8 and nxe2x80x2 is equal to 3; A-represents the amide functional group; and Xxe2x88x92 represents the methyl sulphate ion. If appropriate, the third monomer is acrylic acid.
Moreover, the process of the invention exhibits the following preferred characteristics, considered alone or in combination:
the molar concentration of the second monomer is at least equal to 20% with respect to the final molar concentration of the first and second monomers and of the third monomer, if necessary; this concentration is advantageously at least equal to 25% and at most equal to 40%;
the solvent in which the monomers are reacted is a water/ethanol mixture in a molar ratio preferably varying from 25/75 to 50/50;
the initiator is chosen from 2,2xe2x80x2-azobis(2-amidinopropane) hydrochloride and potassium persulphate;
the first, second and optionally third monomers are reacted under a nitrogen flow.
Another subject-matter of the invention is a textile coated with a copolymer of the invention. This textile is preferably chosen from cotton fabrics and polyester nonfabrics, which are the most frequently employed textiles, in particular in the medical field.
The invention also relates to the use of a copolymer defined above for preparing a textile which is biocidal by contact.